Atherosclerosis is a leading cause of death worldwide. Antioxidant therapy has been considered a promising treatment modality for atherosclerosis, since reactive oxygen species (ROS) play a major role in the pathogenesis of atherosclerosis. We developed ROS-scavenging antioxidant nanoparticles (NPs) that can serve as an effective therapy for atherosclerosis. The newly developed novel antioxidant ROS-eliminating NPs were synthesized via reversible addition–fragmentation chain-transfer (RAFT) polymerization and act as a superoxide dismutase (SOD) mimetic agent. SOD is an anti-ROS enzyme which is difficult to use for passive delivery due to its low half-life and stability. Copolymers were synthesized using different feed ratios of 2,2,6,6-tetramethyl-4-piperidyl methacrylate (PMA) and glycidyl methacrylate (GMA) monomers and an anti-ROS nitroxyl radical polymer was prepared via oxidation. The copolymer was further conjugated with a 6-aminofluorescein via a oxirane ring opening reaction for intracellular delivery in RAW 264.7 cells. The synthesized copolymers were blended to create NPs (∼150 nm size) in aqueous medium and highly stable up to three weeks. The NPs were shown to be taken up by macrophages and to be cytocompatible even at high dose levels (500 μg mL⁻¹). Finally, the nitroxide NPs has been shown to inhibit foam cell formation in macrophages by decreasing internalization of oxidized low-density lipoproteins.

Peptide receptor radionuclide therapy (PRRT) relies on α- and β-emitting radionuclides bound to a peptide that commonly targets somatostatin receptors (SSTRs) for the localized killing of tumors through ionizing radiation. A Lutetium-177 (¹⁷⁷Lu)-based probe linked to the somatostatin analog octreotate ([¹⁷⁷Lu]Lu-DOTA-TATE) is approved for the treatment of certain SSTR-expressing tumors and has been shown to improve survival. However, a limiting factor of PRRT is the potential toxicity derived from the high doses needed to kill the tumor. This could be circumvented by combining PRRT with other treatments for an enhanced anti-tumor effect. Photothermal therapy (PTT) relies on nanoparticle-induced hyperthermia for cancer treatment and could be a useful add-on to PRRT. Here, we investigate a strategy combining [¹⁷⁷Lu]Lu-DOTA-TATE PRRT and nanoshell (NS)-based PTT for the treatment of SSTR-expressing small-cell lung tumors in mice. Our results showed that the combination treatment improved survival compared to PRRT alone, but only when PTT was performed one day after [¹⁷⁷Lu]Lu-DOTA-TATE injection (one of the timepoints examined), showcasing the effect of treatment timing in relation to outcome. Furthermore, the combination treatment was well-tolerated in the mice. This indicates that strategies involving NS-based PTT as an add-on to PRRT could be promising and should be investigated further.

In a longitudinal design, four arterial segments in mice were followed by positron emission tomography/computed tomography (PET/CT) imaging. We aimed to determine how the tracers reflected the development of atherosclerosis via the uptake of 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) for imaging inflammation and [¹⁸F]-sodium fluoride (Na[¹⁸F]F) for imaging active microcalcification in a murine model of atherosclerosis. Apolipoprotein E knock-out (ApoE) mice and C57 BL/6NtaC (B6) mice were divided into four groups. They received either normal chow (N = 7, ApoE mice and N = 6, B6 mice) for 32 weeks or a high-fat diet (N = 6, ApoEHFD mice and N = 9, B6HFD mice) for 32 weeks. The mice were scanned with [¹⁸F]FDG and Na[¹⁸F]F using a dedicated small animal PET/CT scanner at three timepoints. The tracer uptakes in four aortic segments (abdominal aorta, aortic arch, ascending aorta, and thoracic aorta) were measured and reported as SUV_max values. The uptake of [¹⁸F]FDG (SUV_max: 5.7 ± 0.5 vs 1.9 ± 0.2, 230.3%, p = < 0.0001) and Na[¹⁸F]F (SUV_max: 9.6 ± 1.8 vs 4.0 ± 0.3, 175%, p = 0.007) was significantly increased in the abdominal aorta of ApoEHFD mice at Week 32 compared to baseline abdominal aorta values of ApoEHFD mice. [¹⁸F]FDG uptake in the aortic arch, ascending aorta and the thoracic aorta of B6HFD mice at Week 32 showed a robust resemblance to the abdominal aorta uptake whereas the Na[¹⁸F]F uptake only resembled in the thoracic aorta of B6HFD mice at Week 32 compared to the abdominal aorta. The uptake of both [¹⁸F]FDG and Na[¹⁸F]F increased as the disease progressed over time, and the abdominal aorta provided a robust measure across mouse strain and diet. Therefore, it seems to be the preferred region for image readout. For [¹⁸F]FDG-PET, both B6 and ApoE mice provide valuable information and either mouse strain may be used in preclinical cardiovascular studies, whereas for Na[¹⁸F]F -PET, ApoE mice should be preferred.

Urokinase-type plasminogen activator receptor (uPAR) is associated with extracellular matrix (ECM) degradation and cancer aggressiveness. Its role in arterial atherogenesis as a molecular imaging target is not well-established. The aim of this study was to non-invasively visualize uPAR expression in atherosclerosis by a novel uPAR-targeting positron emission tomography (PET) tracer [⁶⁴Cu]Cu-DOTA-AE105. We used molecular biology to investigate uPAR expression by analyzing human atherosclerotic plaques and cultured cells. A retrospective analysis was performed on patients, who underwent combined PET/CT (n = 10) to measure [⁶⁴Cu]Cu-DOTA-AE105 uptake in five large arteries, divided into a high and low-risk group based on coronary artery calcium score (CAC score). The in vitro assay for THP-1 monocytes displayed a significantly upregulated uPAR expression upon stimulation (5.2-fold upregulation, p < 0.0001 by a one-way ANOVA followed by Tukey's test) by single-cell flowcytometric analysis. Freshly excised human atherosclerotic plaques underwent flow cytometric and microarray analyses manifesting 73.9 ± 2.9% of mononuclear phagocyte system (MPS) cells expressing uPAR and had a greater than 7-fold higher gene expression of plasminogen activator urokinase receptor (PLAUR, p = 0.002), integrin subunit alpha X (ITGAX, p = 0.0008), and cluster of differentiation 163 (CD163, p < 0.0001). The tissue-to-background ratios (TBR_max) in five large arteries showed a higher [⁶⁴Cu]Cu-DOTA-AE105 uptake in the group with high CAC score compared to the group with low CAC score (2.4 ± 0.1 vs 1.7 ± 0.1, p = 0.057), significantly higher in the ascending aorta (2.7 ± 0.1 vs 2.0 ± 0.1, p = 0.038) and the abdominal aorta (3.2 ± 0.2 vs 2.0 ± 0.2, p = 0.038) by a non-parametric Mann-Whitney test. uPAR is abundantly expressed by MPS cells in atherosclerotic plaques and can be visualized by the novel PET tracer [⁶⁴Cu]Cu-DOTA-AE105 that may non-invasively detect extracellular matrix remodeling during atherogenesis.

Objectives: We investigated the in vivo biodistribution of vascular cell adhesion molecule-1 (VCAM-1)-targeting polystyrene nanoparticles (PS-NPs) labeled with Rhodamine B in a murine model of atherosclerosis. Methods: Targeted PS-NPs of varying sizes were first assessed for in vitro uptake in RAW264.7 cells. In vivo evaluation with VCAM-1-targeted nanoparticles (NP T) in C57 BL/6NtaC mice was conducted, and organs were analyzed 1, 6, and 24 h post injection, ex vivo. Subsequently, both targeted (NP T) and non-targeted (NP NT) nanoparticles of 30, 60, and 120 nm were injected into Apolipoprotein E knock-out (ApoE KO) mice on a high-fat diet, with ex vivo organ analysis 24 h post injection. Results: Results showed that NP30 T and NP60 T accumulated primarily in the liver and kidney of B6 mice. In ApoE KO mice, biodistribution was largely unaffected by size and targeting, except for higher uptake of NP 120 NT and T in the lungs and spleen. All NP types, except NP60 NT, showed significantly higher signal in ApoE KO mouse aortas compared to saline controls, with no significant differences between NP groups. Conclusions: While nanoparticles accumulated significantly in ApoE KO mouse aortas compared to controls, size and targeting properties did not significantly affect biodistribution in major organs 24 h post injection.